The present invention relates to an apparatus for manufacturing a press jacket for use in the paper making industry. Apparatus and jackets of this type are known from Federal Republic of Germany 37 15 153 A1 , which corresponds to U.S. Pat. No. 5,134,010, issuing Jul. 28, 1992.
The preferred field of use of such press jackets is in the press section of a paper manufacturing machine. In such a machine, the press having the press jacket may be a so called long nip press or extended nip press, such as ones known from
U.S. Pat. No. 4,238,287 (FIG. 1) PA1 U.S. Pat. No. 4,552,620 (FIG. 5) PA1 Federal Republic of Germany OS 32 35 468 (FIG. 1), and PA1 Voith publication "Multi-layer band" (publication reference P 4022 K/0197H/Sh/Sro in the Library of the German Patent Office received on Jul. 26, 1984). Any of these long nip presses may be used in combination with any suitable paper manufacturing machines. PA1 pouring of elastomeric material onto one side of the fabric jacket which had been made endless; PA1 smoothing the resultant surface; PA1 turning the fabric jacket inside out; PA1 pouring the elastomeric material onto the second now outward side of the fabric jacket; PA1 smoothing the second surface and possibly introducing grooves and/or holes in the jacket.
However, in accordance with Federal Republic of Germany OS 35 01 635 (FIG. 6), which corresponds to U.S. Pat. No. Re. 33,034 this press apparatus can also be a press roll having a loosely arranged press jacket in a so-called mat calender. Furthermore, a pressing device can be developed in combination with a press jacket shrunk onto a roll.
Known press jackets are based on flat fabric like pre-products, which are made endless by connecting together the ends of the flat product. They then go through the following successive production steps:
An apparatus for performing the production steps includes a number of features. A pouring body has a series of circumferentially spaced apart, longitudinally extending threads supported above its surface. The pouring body is placed in slow rotation. At the same time, a support bearing for a pouring nozzle for elastomeric material is moved along the longitudinal axis of the pouring body and that bearing also moves the pouring nozzle in this direction along with a feed device for feeding circumferential reinforcing threads to the pouring body. As the pouring nozzle discharges elastomeric material in the direction toward the jacket surface of the pouring body and as the circumferential threads are also delivered by the feed device, the circumferential threads and the elastomeric material are applied along a helical path onto the jacket of the casting body. During this process, the circumferential threads are placed over the longitudinal threads which have already been tensioned. Together these two direction threads form a thread grid. The poured on elastomeric material penetrates through this thread grid and embeds it, and/or the circumferential threads penetrate into the still flowable elastomeric material until they contact the longitudinal threads, depending upon whether the circumferential threads are applied shortly before or after the elastomeric material.
A thread spacing device performs an important function. On the one hand, it maintains a constant distance between the longitudinal threads and the jacket surface of the pouring body. On the other hand, it maintains the distance apart of two adjacent longitudinal threads. This spacing device is developed as a ring which surrounds the pouring body and is displaceable in the axial direction along that body. The ring comprises a distance maintaining ring which rests on the surface of the pouring body and holds the longitudinal threads spaced from the jacket surface of the pouring body. Behind the thread spacing maintaining ring, as seen in the direction of displacement of the support, another ring is arranged. It is developed like a comb with teeth engaging through the space between two adjacent longitudinal threads. The teeth are of a width equal to the desired distance between two longitudinal threads.
The known spacing device has one serious problem. The circumferences of the press jackets have recently become larger. Therefore, the pouring body must be made correspondingly larger in diameter as must the ring shaped spacing devices. Such rings are more difficult to manufacture, are of greater weight, and are heavy and more difficult to handle. There is the danger that upon their displacement along the pouring body, the rings will cant during the manufacture of the press jacket.